Pigmentless embryos???

I need to make zebrafish without eye pigment to check for expression of a gene
in the eye. Does anyone have experience using PTU? I've worked with PTU
enough to know it is pretty insoluble. I notice the Zeb Book says 0.003% PTU
in Hanks. Do you just put in enought PTU to pretend it is 0.003% or is there
some trick to getting it to go into solution? Any advice is welcome. Thanks
Dick Vogt